Re: [time-nuts] Frequency satndard on ebay UK / sulzer manuals
Dear Tom, Luciano, all, Thank you for your comments. The Sulzer is not intended to be used as a high accuracy standard. The oscillator fits nicely to some old radio's ;-) However, I think (not measured) that stability of the oscillator is better then the average stability of a modern low budget oscillator. Therefore it would be nice to have it up and running. The schematic on the website of Tom was very helpful. Basically it would be sufficient for trouble-shooting/repair. However, I would like to figure out the numbers which should be indicated by the moving coil meter on the front. I did a quick measurement with a HP counter 53230A (without a very stable reference). The number shown for the allen variation (after a couple of hours) was 1.5mHz on the 5MHz signal. (Maybe this number shows the stability of the HP??) This number gives good hope, according to me. Is there a source for manuals on these instruments? I checked the site of KO4BB, unfortunately he doesn't have a PDF of the manual. Best regards, Jeroen On 09/17/2012 02:50 PM, Timeok wrote: Yes Tom you right, but your example is on a rare Sulzer 2.5 MHz. Another very good reference can be an HP 106 (quasi impossible to find). This is not valid for the Racal model as described. I have had several unit of this standar under test and I keep one for my personal small museum. I have also a Suzer 5 MHz, it is better than Racal but same as performance to several others. I have an HP 107Br but it is not working and I cannot test it at the moment. All us are looking to find some units in flea market, old and good, but this is a very rare event due the fact there is a large 5e-10 (OCXO)production or lower, and few top performance products as you describe. good luck to us! Luciano Il 2012-09-14 19:32 Tom Van Baak ha scritto: This equipment is only good to spend winter time or for museum. Several newer oscillator,like HP10811/10544, have the same characteristics or better in smaller size. The component used ar not the best and you can have fault expecially on the power supply. Luciano, My experience is that some of these old 2.5 or 5 MHz Sulzer oscillators have vastly better performance than most 10811/10544. For example, see: http://www.febo.com/pages/oscillators/sulzer/ http://leapsecond.com/museum/sul25-1/ http://leapsecond.com/museum/sul25-2/ While it is true that they don't always work out-of-the-box when you find them cheap on eBay, once fixed, their performance is stunning. That's why these rare old Sulzer's are highly prized. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
In message 5058061f.6040...@clanbaker.org, Michael Baker writes: I was wondering, after seeing some 100 watt LED series wired assemblies that were listed at 30-34 VDC @ 2.9A if a number of LEDs could be wired in series and powered directly from a rectified 110 VAC power source. You wouldn't want that, the flickering would be unbearable. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency satndard on ebay UK / sulzer manuals
Hi Jeroen, I have a paper copy of the SULZER 5A (the 5 MHz version) and of the Racal. If you want I can make a paper copy and send you it by postal service. I do not know if Tom have a pdf copy of the manuals. Me too have these OCXO for passion. I suggest you to buy e ceep GPSDO and use it as reference for your counter, so you can start to do accurate measurement and compare the standard you have (or will have) in your lab. Let me know, for logistic use my direct email: tim...@timeok.it Luciano IZ5JHJ www.timeok.it Il 2012-09-18 09:04 Jeroen Bastemeijer ha scritto: Dear Tom, Luciano, all, Thank you for your comments. The Sulzer is not intended to be used as a high accuracy standard. The oscillator fits nicely to some old radio's ;-) However, I think (not measured) that stability of the oscillator is better then the average stability of a modern low budget oscillator. Therefore it would be nice to have it up and running. The schematic on the website of Tom was very helpful. Basically it would be sufficient for trouble-shooting/repair. However, I would like to figure out the numbers which should be indicated by the moving coil meter on the front. I did a quick measurement with a HP counter 53230A (without a very stable reference). The number shown for the allen variation (after a couple of hours) was 1.5mHz on the 5MHz signal. (Maybe this number shows the stability of the HP??) This number gives good hope, according to me. Is there a source for manuals on these instruments? I checked the site of KO4BB, unfortunately he doesn't have a PDF of the manual. Best regards, Jeroen On 09/17/2012 02:50 PM, Timeok wrote: Yes Tom you right, but your example is on a rare Sulzer 2.5 MHz. Another very good reference can be an HP 106 (quasi impossible to find). This is not valid for the Racal model as described. I have had several unit of this standar under test and I keep one for my personal small museum. I have also a Suzer 5 MHz, it is better than Racal but same as performance to several others. I have an HP 107Br but it is not working and I cannot test it at the moment. All us are looking to find some units in flea market, old and good, but this is a very rare event due the fact there is a large 5e-10 (OCXO)production or lower, and few top performance products as you describe. good luck to us! Luciano Il 2012-09-14 19:32 Tom Van Baak ha scritto: This equipment is only good to spend winter time or for museum. Several newer oscillator,like HP10811/10544, have the same characteristics or better in smaller size. The component used ar not the best and you can have fault expecially on the power supply. Luciano, My experience is that some of these old 2.5 or 5 MHz Sulzer oscillators have vastly better performance than most 10811/10544. For example, see: http://www.febo.com/pages/oscillators/sulzer/ http://leapsecond.com/museum/sul25-1/ http://leapsecond.com/museum/sul25-2/ While it is true that they don't always work out-of-the-box when you find them cheap on eBay, once fixed, their performance is stunning. That's why these rare old Sulzer's are highly prized. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- timeok ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
Hm Maybe if an 1:1 isolation transformer is used except that it would be too heavy and large Mike Baker Mike, As long as one is spending on a transformer.. might as well use a step down transformer and use lower voltage lights! Raj ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency satndard on ebay UK / sulzer manuals
Dear Luciano, Thank you for your offer to make copies of the manuals. If it is OK with you, I can make a PDF-scan of the manuals and send them to KO4BB to be put on his website. I will contact you offlist for my address details. Luckily enough I have a GPSDO, but... the GPSDO is at home and the counter is at work. A challenge to get these two together ;-) Best regards, Jeroen PE1RGE On 09/18/2012 10:30 AM, Timeok wrote: Hi Jeroen, I have a paper copy of the SULZER 5A (the 5 MHz version) and of the Racal. If you want I can make a paper copy and send you it by postal service. I do not know if Tom have a pdf copy of the manuals. Me too have these OCXO for passion. I suggest you to buy e ceep GPSDO and use it as reference for your counter, so you can start to do accurate measurement and compare the standard you have (or will have) in your lab. Let me know, for logistic use my direct email: tim...@timeok.it Luciano IZ5JHJ www.timeok.it Il 2012-09-18 09:04 Jeroen Bastemeijer ha scritto: Dear Tom, Luciano, all, Thank you for your comments. The Sulzer is not intended to be used as a high accuracy standard. The oscillator fits nicely to some old radio's ;-) However, I think (not measured) that stability of the oscillator is better then the average stability of a modern low budget oscillator. Therefore it would be nice to have it up and running. The schematic on the website of Tom was very helpful. Basically it would be sufficient for trouble-shooting/repair. However, I would like to figure out the numbers which should be indicated by the moving coil meter on the front. I did a quick measurement with a HP counter 53230A (without a very stable reference). The number shown for the allen variation (after a couple of hours) was 1.5mHz on the 5MHz signal. (Maybe this number shows the stability of the HP??) This number gives good hope, according to me. Is there a source for manuals on these instruments? I checked the site of KO4BB, unfortunately he doesn't have a PDF of the manual. Best regards, Jeroen On 09/17/2012 02:50 PM, Timeok wrote: Yes Tom you right, but your example is on a rare Sulzer 2.5 MHz. Another very good reference can be an HP 106 (quasi impossible to find). This is not valid for the Racal model as described. I have had several unit of this standar under test and I keep one for my personal small museum. I have also a Suzer 5 MHz, it is better than Racal but same as performance to several others. I have an HP 107Br but it is not working and I cannot test it at the moment. All us are looking to find some units in flea market, old and good, but this is a very rare event due the fact there is a large 5e-10 (OCXO)production or lower, and few top performance products as you describe. good luck to us! Luciano Il 2012-09-14 19:32 Tom Van Baak ha scritto: This equipment is only good to spend winter time or for museum. Several newer oscillator,like HP10811/10544, have the same characteristics or better in smaller size. The component used ar not the best and you can have fault expecially on the power supply. Luciano, My experience is that some of these old 2.5 or 5 MHz Sulzer oscillators have vastly better performance than most 10811/10544. For example, see: http://www.febo.com/pages/oscillators/sulzer/ http://leapsecond.com/museum/sul25-1/ http://leapsecond.com/museum/sul25-2/ While it is true that they don't always work out-of-the-box when you find them cheap on eBay, once fixed, their performance is stunning. That's why these rare old Sulzer's are highly prized. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
Hi I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Tuesday, September 18, 2012 1:35 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Hi Power LED Light power supply... LEDs change brightness very fast and will flicker at 120Hz if you do that. Many people can see 120Hz flicker. Also you would not be getting all the brightness you could. Better to low pass filter On Mon, Sep 17, 2012 at 10:26 PM, Michael Baker mp...@clanbaker.org wrote: Time-Nutters-- I was wondering, after seeing some 100 watt LED series wired assemblies that were listed at 30-34 VDC @ 2.9A if a number of LEDs could be wired in series and powered directly from a rectified 110 VAC power source. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Z3801 Replacement GPS Receiver Card
On 9/17/2012 6:03 PM, time-nuts-requ...@febo.com wrote: OK, you can test a VP Oncore GPS receiver alone if you have a mean to translate the TTL serial port to a regular RS232 for the PC. This can be done with a MAX232 chip (or equivalent). Then the pinout (refer to the FYI, I've had really good luck with these over the years: http://www.digikey.com/product-detail/en/TTL-232R-5V/768-1028-ND/2003493 http://www.digikey.com/product-detail/en/TTL-232R-3V3/768-1015-ND/1836393 The big thing is the drivers are really well written. The seem to be able to talk to anything I point them at. Never found any software they don't like (yet) ... I keep a few around, just in case. Dan ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] 100 watt higher LED power supply...
Time-Nutters-- OK-- So flicker would be objectionable running off a rectified 110VAC line.My thinking was to find a way around needing a current limiter that would waste energy as heat. Rectifying (and some filtering) of the 110AC line seemed to be one approach. I am thinking of building a several hundred watt LED light for over my workbench by mounting the LEDs on an existing frame for a 4-lamp (long-tube) fluorescent lamp fixture and using the large surface area of the metal frame as a heat sink. The 100 watt LEDS are on eBay but I have not seen the current-limiting drivers for them on eBay. Mike Baker ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
Shouldn't be a problem with the standard UV - phosphor style white LED's that are on the market today. The phosphor has a hang time that runs into the minutes, if all of the glowing LED bits in my lamps are an indication. They glow softly for several minutes after turn off. -Chuck Harris Chris Albertson wrote: LEDs change brightness very fast and will flicker at 120Hz if you do that. Many people can see 120Hz flicker. Also you would not be getting all the brightness you could. Better to low pass filter On Mon, Sep 17, 2012 at 10:26 PM, Michael Baker mp...@clanbaker.org wrote: Time-Nutters-- I was wondering, after seeing some 100 watt LED series wired assemblies that were listed at 30-34 VDC @ 2.9A if a number of LEDs could be wired in series and powered directly from a rectified 110 VAC power source. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
In message ac9e4c92327746d4a521facd35d9d...@vectron.com, Bob Camp writes: I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) I suggest you either carry out a couple of experiments yourself, or go a little easy on the irony. CRTs, and LCDs go out of their way to avoid flickering using physical or electronic persistence, whereas a naked LED wil happily flash up to several hundred kHz if you ask it to. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 100 watt higher LED power supply...
Boy I have been staying clear of this discussion. Pretty sure they make drop in led tubes now at $$$ Its funny we speak to a 100 watt lamp. But for a led that would be something like 24 watts. It makes no sense to speak in watts. Instead Lumens. I think we want the luminisity of a 100 watt incandescent bulb. Was in a hotel elevator last week that had replaced the overhead lamps with 4 chip LEDs. Both the intensity and color were very impressive. I was thinking great for the bench. Wanted to unscrew one and see who made them. It was the small form factor like Halogen. Regards Paul WB8TSL On Tue, Sep 18, 2012 at 8:56 AM, Michael Baker mp...@clanbaker.org wrote: Time-Nutters-- OK-- So flicker would be objectionable running off a rectified 110VAC line.My thinking was to find a way around needing a current limiter that would waste energy as heat. Rectifying (and some filtering) of the 110AC line seemed to be one approach. I am thinking of building a several hundred watt LED light for over my workbench by mounting the LEDs on an existing frame for a 4-lamp (long-tube) fluorescent lamp fixture and using the large surface area of the metal frame as a heat sink. The 100 watt LEDS are on eBay but I have not seen the current-limiting drivers for them on eBay. Mike Baker __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
Hi The shutter on a conventional movie projector is very much an on / off device. They run well below 120Hz. The phosphors in a white LED are at least as long persistence as those in a TV set. There are a *lot* of TV's out there that refresh at 60 Hz or less. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Poul-Henning Kamp Sent: Tuesday, September 18, 2012 9:05 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Hi Power LED Light power supply... In message ac9e4c92327746d4a521facd35d9d...@vectron.com, Bob Camp writes: I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) I suggest you either carry out a couple of experiments yourself, or go a little easy on the irony. CRTs, and LCDs go out of their way to avoid flickering using physical or electronic persistence, whereas a naked LED wil happily flash up to several hundred kHz if you ask it to. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] PLL behavior
I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're not trying to track noise).. What I'm particularly interested in is the behavior in the PLL when the reference returns. The overall situation is where we are trying to make a frequency/phase measurement over 10-100 seconds, where the reference has a 50% duty cycle, and is on for a second, off for a second. I can fairly simply model this, or just try it, but I'm looking for some references to an analytical approach. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 100 watt higher LED power supply...
Hi Paul; I started thinking about this project because we are installing a new EMC room at work and thought we could use totally eliminate lighting as a noise source with LED lighting. Allowing lighting during even the most precise measurements. While researching I ran across some amazing items on eBay out of China. I was talking about these raw chip arrays in which a 100watts means it consumes 100watts like 400-800watt in conventional incandescent light. The LED's are also more directional so in a number of applications the seem Lumen output may produce more LUX where needed. Light Temp is another big deal. In all these products their claimed ratings and actual ratings can very different. I prefer actual wattage since it seems the most accurate rating, but it took some time to understand the different efficiencies between product type. I will most likely go with a larger number of lower wattage arrays, and mix and match color temp to taste. My ultimate goal is to greatly improve my current lighting to make up for my aging eyes while at the same time lower lab noise. I also hope the increased efficiency will help with temperature stability around the lab while saving energy. Last, I was hoping to do it for about the price of replacement bulbs in my current lighting. Thomas Knox Date: Tue, 18 Sep 2012 09:47:23 -0400 From: paulsw...@gmail.com To: time-nuts@febo.com Subject: Re: [time-nuts] 100 watt higher LED power supply... Boy I have been staying clear of this discussion. Pretty sure they make drop in led tubes now at $$$ Its funny we speak to a 100 watt lamp. But for a led that would be something like 24 watts. It makes no sense to speak in watts. Instead Lumens. I think we want the luminisity of a 100 watt incandescent bulb. Was in a hotel elevator last week that had replaced the overhead lamps with 4 chip LEDs. Both the intensity and color were very impressive. I was thinking great for the bench. Wanted to unscrew one and see who made them. It was the small form factor like Halogen. Regards Paul WB8TSL On Tue, Sep 18, 2012 at 8:56 AM, Michael Baker mp...@clanbaker.org wrote: Time-Nutters-- OK-- So flicker would be objectionable running off a rectified 110VAC line.My thinking was to find a way around needing a current limiter that would waste energy as heat. Rectifying (and some filtering) of the 110AC line seemed to be one approach. I am thinking of building a several hundred watt LED light for over my workbench by mounting the LEDs on an existing frame for a 4-lamp (long-tube) fluorescent lamp fixture and using the large surface area of the metal frame as a heat sink. The 100 watt LEDS are on eBay but I have not seen the current-limiting drivers for them on eBay. Mike Baker __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Z3801 Replacement GPS Receiver Card
TTL to USB serial adapters on ebay for very reasonable. Don Dan Kemppainen On 9/17/2012 6:03 PM, time-nuts-requ...@febo.com wrote: OK, you can test a VP Oncore GPS receiver alone if you have a mean to translate the TTL serial port to a regular RS232 for the PC. This can be done with a MAX232 chip (or equivalent). Then the pinout (refer to the FYI, I've had really good luck with these over the years: http://www.digikey.com/product-detail/en/TTL-232R-5V/768-1028-ND/2003493 http://www.digikey.com/product-detail/en/TTL-232R-3V3/768-1015-ND/1836393 The big thing is the drivers are really well written. The seem to be able to talk to anything I point them at. Never found any software they don't like (yet) ... I keep a few around, just in case. Dan ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PLL behavior
won't it depend almost entirely on the charge pump filter? Don Jim Lux I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're not trying to track noise).. What I'm particularly interested in is the behavior in the PLL when the reference returns. The overall situation is where we are trying to make a frequency/phase measurement over 10-100 seconds, where the reference has a 50% duty cycle, and is on for a second, off for a second. I can fairly simply model this, or just try it, but I'm looking for some references to an analytical approach. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 100 watt higher LED power supply...
On Tue, Sep 18, 2012 at 5:56 AM, Michael Baker mp...@clanbaker.org wrote: Time-Nutters-- OK-- So flicker would be objectionable running off a rectified 110VAC line.My thinking was to find a way around needing a current limiter that would waste energy as heat. Even if flicker were not a problem what happens if the AC line voltage goes up? How to prevent over driving the LEDS. Or a voltage spike on the AC mains. I think you ned some kind of line regulation. Andin a 100W system you will have heat. The LED's current draw depends on temperature so you'd need some load regulation too. Or another way around the need for regulation is to run the LEDS at reduced power so there is a large safety margin for heat and line voltage variation. But then you need more LEDs for the same amount of light. A constant current DC power supply is not that hard nor expensive but if LEDs are cheap enough just get 2X more of then and run them at 1/2 rated current. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PLL behavior
Hi Gardner in Phaselock Techniques has figure 4.8 that is a pretty good starting point. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: Tuesday, September 18, 2012 11:29 AM To: Discussion of precise time and frequency measurement Subject: [time-nuts] PLL behavior I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're not trying to track noise).. What I'm particularly interested in is the behavior in the PLL when the reference returns. The overall situation is where we are trying to make a frequency/phase measurement over 10-100 seconds, where the reference has a 50% duty cycle, and is on for a second, off for a second. I can fairly simply model this, or just try it, but I'm looking for some references to an analytical approach. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PLL behavior
Usually in a regular PLL the missing reference should pull the output at the lowest voltage: as if the input frequency is too high. It helps if the charge pump output can be disabled when the reference stops: in this case the output voltage will go down following the droop of the integrator/filter. On Tue, Sep 18, 2012 at 5:39 PM, Don Latham d...@montana.com wrote: won't it depend almost entirely on the charge pump filter? Don Jim Lux I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're not trying to track noise).. What I'm particularly interested in is the behavior in the PLL when the reference returns. The overall situation is where we are trying to make a frequency/phase measurement over 10-100 seconds, where the reference has a 50% duty cycle, and is on for a second, off for a second. I can fairly simply model this, or just try it, but I'm looking for some references to an analytical approach. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 100 watt higher LED power supply...
Hi A LED is indeed a diode. It's current changes pretty fast as voltage changes. It's voltage drop also highly temperature dependant. Driving one with a constant voltage and no current limiting is a very tough proposition. You would need to feedback the temperature of the device and adjust the supply accordingly. It's much easier to do this some sort of current feedback. Compared to raw rectified AC, current regulation will also keep you from blowing out the entire array when there's a spike on the supply line. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Tuesday, September 18, 2012 11:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 100 watt higher LED power supply... On Tue, Sep 18, 2012 at 5:56 AM, Michael Baker mp...@clanbaker.org wrote: Time-Nutters-- OK-- So flicker would be objectionable running off a rectified 110VAC line.My thinking was to find a way around needing a current limiter that would waste energy as heat. Even if flicker were not a problem what happens if the AC line voltage goes up? How to prevent over driving the LEDS. Or a voltage spike on the AC mains. I think you ned some kind of line regulation. Andin a 100W system you will have heat. The LED's current draw depends on temperature so you'd need some load regulation too. Or another way around the need for regulation is to run the LEDS at reduced power so there is a large safety margin for heat and line voltage variation. But then you need more LEDs for the same amount of light. A constant current DC power supply is not that hard nor expensive but if LEDs are cheap enough just get 2X more of then and run them at 1/2 rated current. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Z3801 Replacement GPS Receiver Card
Hi If you go the eBay route, the FTDI chip set (as mentioned in the links below) is very much the one you want to get. There are several other chip sets out there. I have yet to see one that's as solid as the FTDI's. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Don Latham Sent: Tuesday, September 18, 2012 11:35 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Z3801 Replacement GPS Receiver Card TTL to USB serial adapters on ebay for very reasonable. Don Dan Kemppainen On 9/17/2012 6:03 PM, time-nuts-requ...@febo.com wrote: OK, you can test a VP Oncore GPS receiver alone if you have a mean to translate the TTL serial port to a regular RS232 for the PC. This can be done with a MAX232 chip (or equivalent). Then the pinout (refer to the FYI, I've had really good luck with these over the years: http://www.digikey.com/product-detail/en/TTL-232R-5V/768-1028-ND/2003493 http://www.digikey.com/product-detail/en/TTL-232R-3V3/768-1015-ND/1836393 The big thing is the drivers are really well written. The seem to be able to talk to anything I point them at. Never found any software they don't like (yet) ... I keep a few around, just in case. Dan ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 100 watt higher LED power supply...
You really want to drive the LEDs with switcher designs typical in battery chargers, basically hysteretic current output. Prior to LIon batteries (which are voltage sensitive), the old nicad/NiMH chargers used the hysteretic scheme. If you want a simpler switcher, you can take the garden variety voltage regulated switcher and hack it to be current regulated. LTC and Micrel sell chips for exactly that use. Note that the really bright LEDs are designed for a 10 year life at those power levels. (Sadly, true for LED backlit TVs.) I was at a trade show where CREE had a display. For natural lighthing, they mix some red LEDs in with the white LEDs. Uh, the dope growing LED fixtures do the same thing. ;-) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
On Tue, Sep 18, 2012 at 5:21 AM, Bob Camp li...@rtty.us wrote: Hi I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) In the old CRT type TV sets, the phosphor has some persistence. Movies are modulated with a square waves, the frame blinks off and goes dark then blinks on. But the LED's brightness is fast enough to track the sine wave and would be bright only for an instant with quick pulses of light. But just as bad as the flicker is that the LED is wasted and spends most of the time being dim. Power supplies are so easy to do that they are NOT the hard part. With LEDS the hard part is the mechanical and optical design. The light must be indirect and defused and to do that correctly and without much waste requires being creative and/or having some metal working skills. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PLL behavior
If you break the DC control chain of the PLL with a A2D and a controller and back with a D2A .. you would program the control with any kind of behavior you want. Just a thought! Raj, vu2zap At 18-09-2012, you wrote: I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're not trying to track noise).. What I'm particularly interested in is the behavior in the PLL when the reference returns. The overall situation is where we are trying to make a frequency/phase measurement over 10-100 seconds, where the reference has a 50% duty cycle, and is on for a second, off for a second. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Z3801 Replacement GPS Receiver Card
Dan Kemppainen wrote: On 9/17/2012 6:03 PM, time-nuts-requ...@febo.com wrote: OK, you can test a VP Oncore GPS receiver alone if you have a mean to translate the TTL serial port to a regular RS232 for the PC. This can be done with a MAX232 chip (or equivalent). Then the pinout (refer to the FYI, I've had really good luck with these over the years: http://www.digikey.com/product-detail/en/TTL-232R-5V/768-1028-ND/2003493 http://www.digikey.com/product-detail/en/TTL-232R-3V3/768-1015-ND/1836393 The big thing is the drivers are really well written. The seem to be able to talk to anything I point them at. Never found any software they don't like (yet) ... Even better... using the free programming utility on their website you can set the data lines ( handshaking if you need) to inverted. Then there's no need to add an inverting stage to the VP UART. Mike ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
Hi A white LED is like a fluorescent bulb. The actual LED runs at UV and there are phosphors in it to convert the UV to various colors of visible light. The phosphor mix determines the color balance of the LED. It also adds persistence to the output, just like a CRT. I do very much agree that you need a proper supply to run the LED's. Rectified AC is *not* the way to go. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Tuesday, September 18, 2012 12:42 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Hi Power LED Light power supply... On Tue, Sep 18, 2012 at 5:21 AM, Bob Camp li...@rtty.us wrote: Hi I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) In the old CRT type TV sets, the phosphor has some persistence. Movies are modulated with a square waves, the frame blinks off and goes dark then blinks on. But the LED's brightness is fast enough to track the sine wave and would be bright only for an instant with quick pulses of light. But just as bad as the flicker is that the LED is wasted and spends most of the time being dim. Power supplies are so easy to do that they are NOT the hard part. With LEDS the hard part is the mechanical and optical design. The light must be indirect and defused and to do that correctly and without much waste requires being creative and/or having some metal working skills. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
li...@rtty.us said: There are a *lot* of TV's out there that refresh at 60 Hz or less. Many years ago, we had a busted fluorescent light at work. I could see the flicker out of the corner of my eye. I found it annoying, so I'm a firm believer that some people can see flicker in some conditions. (Fortunately, it was in a location where I didn't spend much time.) Direct vision was not a problem. I assumed the lamp was running at 60 Hz rather than 120 and that peripheral vision was better at detecting flicker/motion. Wiki has an interesting page on this stuff: http://en.wikipedia.org/wiki/Flicker_fusion_threshold the rod cells of the human eye have a faster response time than the cone cells, so flicker can be sensed in peripheral vision at higher frequencies than in foveal vision But also: The maximum fusion frequency for rod-mediated vision reaches a plateau at about 15 Hz, whereas cones reach a plateau, observable only at very high illumination intensities, of about 60 Hz (I think that is backwards from the previous line. I'd guess somebody typoed rods-cones.) Note that LEDs without diffusion are high-illumination, so I'm not surprised if some people report flicker troubles. It would be interesting to investigate some examples. I wonder if they are 120 Hz or 60 Hz? More wiki: For the purposes of presenting moving images, the human flicker fusion threshold is usually taken as 16 hertz (Hz). In actual practice, movies are recorded at 24 frames per second, and TV cameras operate at 25 or 30 frames per second, depending on the TV system used. Even though motion may seem to be continuous at 25 or 30 frame/s, the brightness may still seem to flicker objectionably. By showing each frame twice in cinema projection (48 Hz), and using interlace in television (50 or 60 Hz), a reasonable margin of error for unusual viewing conditions is achieved in minimising subjective flicker effects. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
If you all check, they are using LEDs in traffic signals now by the thousands. These are variations of multiple LEDs used in these signals and they are all powered by 115vac thru the traffic controllers. Joe k3wry In a message dated 9/18/2012 1:28:18 A.M. Eastern Daylight Time, mp...@clanbaker.org writes: Time-Nutters-- I was wondering, after seeing some 100 watt LED series wired assemblies that were listed at 30-34 VDC @ 2.9A if a number of LEDs could be wired in series and powered directly from a rectified 110 VAC power source. If enough LEDs are wired in series such that the peak DC voltage from the rectified 110 AC line does not exceed the max current rating of the LEDs this should eliminate any excess current from flowing. Obviously, this does not provide for any safety isolation from the line. Hm Maybe if an 1:1 isolation transformer is used except that it would be too heavy and large Mike Baker -- ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
Hi ... and if you take a hammer to one, they have a cheap little switcher built right into the base of the bulb. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of k3...@aol.com Sent: Tuesday, September 18, 2012 1:24 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Hi Power LED Light power supply... If you all check, they are using LEDs in traffic signals now by the thousands. These are variations of multiple LEDs used in these signals and they are all powered by 115vac thru the traffic controllers. Joe k3wry In a message dated 9/18/2012 1:28:18 A.M. Eastern Daylight Time, mp...@clanbaker.org writes: Time-Nutters-- I was wondering, after seeing some 100 watt LED series wired assemblies that were listed at 30-34 VDC @ 2.9A if a number of LEDs could be wired in series and powered directly from a rectified 110 VAC power source. If enough LEDs are wired in series such that the peak DC voltage from the rectified 110 AC line does not exceed the max current rating of the LEDs this should eliminate any excess current from flowing. Obviously, this does not provide for any safety isolation from the line. Hm Maybe if an 1:1 isolation transformer is used except that it would be too heavy and large Mike Baker -- ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PLL behavior
On 9/18/12 8:39 AM, Don Latham wrote: won't it depend almost entirely on the charge pump filter? Classic PLL with a mixer, not with a Phase Frequency Detector and charge pump.. But yes, it depends in large part on the loop filter, but also on the behavior of the oscillator.. (i.e. where does it go with fixed tune input) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
On 9/18/12 6:54 AM, Bob Camp wrote: Hi The shutter on a conventional movie projector is very much an on / off device. They run well below 120Hz. Actually, the typical movie projector uses a rotary shutter which runs at twice the frame rate (e.g. 48 flashes/second) and is hardly a fast transition. The actual waveform is more like a trapezoid (imagine a narrow beam of light going through a rotating disk with two sectors in it..) There's also noticeable movement of the film as the shutter is opening and closing, however, your eye/brain is pretty immune to overall image shifts, particularly when it fills the field of view: it's not much different than handling the saccades of your normal eye movements. 24 fps is quite visible to most people (hence interlace on TVs to get 50 or 60 fields/second) The phosphors in a white LED are at least as long persistence as those in a TV set. There are a *lot* of TV's out there that refresh at 60 Hz or less. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Poul-Henning Kamp Sent: Tuesday, September 18, 2012 9:05 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Hi Power LED Light power supply... In message ac9e4c92327746d4a521facd35d9d...@vectron.com, Bob Camp writes: I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) I suggest you either carry out a couple of experiments yourself, or go a little easy on the irony. CRTs, and LCDs go out of their way to avoid flickering using physical or electronic persistence, whereas a naked LED wil happily flash up to several hundred kHz if you ask it to. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
I remember reading that Hollywood played with faster frame rates and found a substantial number of people experience motion sickness. Thomas Knox Date: Tue, 18 Sep 2012 10:51:07 -0700 From: jim...@earthlink.net To: time-nuts@febo.com Subject: Re: [time-nuts] Hi Power LED Light power supply... On 9/18/12 6:54 AM, Bob Camp wrote: Hi The shutter on a conventional movie projector is very much an on / off device. They run well below 120Hz. Actually, the typical movie projector uses a rotary shutter which runs at twice the frame rate (e.g. 48 flashes/second) and is hardly a fast transition. The actual waveform is more like a trapezoid (imagine a narrow beam of light going through a rotating disk with two sectors in it..) There's also noticeable movement of the film as the shutter is opening and closing, however, your eye/brain is pretty immune to overall image shifts, particularly when it fills the field of view: it's not much different than handling the saccades of your normal eye movements. 24 fps is quite visible to most people (hence interlace on TVs to get 50 or 60 fields/second) The phosphors in a white LED are at least as long persistence as those in a TV set. There are a *lot* of TV's out there that refresh at 60 Hz or less. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Poul-Henning Kamp Sent: Tuesday, September 18, 2012 9:05 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Hi Power LED Light power supply... In message ac9e4c92327746d4a521facd35d9d...@vectron.com, Bob Camp writes: I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) I suggest you either carry out a couple of experiments yourself, or go a little easy on the irony. CRTs, and LCDs go out of their way to avoid flickering using physical or electronic persistence, whereas a naked LED wil happily flash up to several hundred kHz if you ask it to. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
The local sandwich shop that I frequent recently switched to LED lighting. When I walk up to the counter I can see the flicker when people's hands are moving. The same applies for LED taillights when a vehicle is moving as well as newer LED tower lighting. Bob On Sep 18, 2012, at 13:15, Hal Murray hmur...@megapathdsl.net wrote: li...@rtty.us said: There are a *lot* of TV's out there that refresh at 60 Hz or less. Many years ago, we had a busted fluorescent light at work. I could see the flicker out of the corner of my eye. I found it annoying, so I'm a firm believer that some people can see flicker in some conditions. (Fortunately, it was in a location where I didn't spend much time.) Direct vision was not a problem. I assumed the lamp was running at 60 Hz rather than 120 and that peripheral vision was better at detecting flicker/motion. Wiki has an interesting page on this stuff: http://en.wikipedia.org/wiki/Flicker_fusion_threshold the rod cells of the human eye have a faster response time than the cone cells, so flicker can be sensed in peripheral vision at higher frequencies than in foveal vision But also: The maximum fusion frequency for rod-mediated vision reaches a plateau at about 15 Hz, whereas cones reach a plateau, observable only at very high illumination intensities, of about 60 Hz (I think that is backwards from the previous line. I'd guess somebody typoed rods-cones.) Note that LEDs without diffusion are high-illumination, so I'm not surprised if some people report flicker troubles. It would be interesting to investigate some examples. I wonder if they are 120 Hz or 60 Hz? More wiki: For the purposes of presenting moving images, the human flicker fusion threshold is usually taken as 16 hertz (Hz). In actual practice, movies are recorded at 24 frames per second, and TV cameras operate at 25 or 30 frames per second, depending on the TV system used. Even though motion may seem to be continuous at 25 or 30 frame/s, the brightness may still seem to flicker objectionably. By showing each frame twice in cinema projection (48 Hz), and using interlace in television (50 or 60 Hz), a reasonable margin of error for unusual viewing conditions is achieved in minimising subjective flicker effects. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
If you take your garden variety boost converter and place a resistor as the load, the current in the inductor is regulated. (Current is vreference over this resistor value.) All these dedicated LED drive chips do is reduce the voltage across the resistor to improve efficiency. In addition, they might have an overvoltage protection scheme. If for some reason the load, namely the LED string, is removed, the boost converter will self destruct. Unlikely to happen if everything is soldered together, but LEDs are external, and possibly connection can get loose. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
On 18 Sep, 2012, at 12:42 , Chris Albertson wrote: On Tue, Sep 18, 2012 at 5:21 AM, Bob Camp li...@rtty.us wrote: Hi I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) In the old CRT type TV sets, the phosphor has some persistence. Movies are modulated with a square waves, the frame blinks off and goes dark then blinks on. But the LED's brightness is fast enough to track the sine wave and would be bright only for an instant with quick pulses of light. Just to add to this... Ontario, Canada originally ran its power grid at 25 Hz. When they switched the grid to 60 Hz in the 1930's some of the industrial power users, particularly in northern Ontario where private (usually hydroelectric) power generators were common, never got around to changing their plants over. Mine and paper mills using 25 Hz power were common as recently as the 1980's, and might still be there for all I know. Standard incandescent light bulbs don't have a lot of persistence when run on 25 Hz power (I assume there might have been a time when you could buy incandescent bulbs designed for 25 Hz, but not in my lifetime). They don't go entirely off, but they get significantly dimmer in the visible spectrum in the dips as the output red-shifts towards the infrared; they follow the sine pretty well. In my teens, when visiting a place using 25 Hz power for lighting, I could initially see an incredibly annoying flicker when I first got there but after a minute or two this would fade and I'd no longer notice it. Some other people would also see the flicker but others, including my parents, couldn't see it at all so there seemed to be variation (maybe age-related, maybe not) among individual abilities to see this. I would hence believe that a 50 Hz flicker must be pretty close to the edge of what can be perceived, so I'm having trouble believing that a flicker at more than twice that rate would be perceptible at all by anyone. Dennis Ferguson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Reducing lab noise with LED lighting
You have apparently not tried any modern/quality LED bulbs. The Sylvania Ultra series have a 95 CRI (color rendering index). Bridgelux makes some arrays with a CRI over 98. I defy you to tell the difference between the output of those bulbs (or any LED with a CRI over 85) and halogens. My house has a lot of artwork that is now lit by LEDs. I've has a couple of museum directors by and they couldn't. As far as LED flicker is concerned, lots of LED flashlights dim via a PWM signal. Lots of people can see PWM effects up to over 400 Hz! It shows up like a strobe light effect when the beam is moved around. Also, white LEDs are NOT pumped by UV. The LED underneath the phosphor is a royal blue color. Lighting LEDs produce no spectrum in the UV or IR bands... that is one reason museums and art galleries use them. -- Personally I find the light spectrum from the CFL's and LED's to be very unpleasant. I have had to add an incandescent to the lighting in my office to keep my eyes from straining. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 98, Issue 77
On 9/18/2012 1:48 PM, time-nuts-requ...@febo.com wrote: In the old CRT type TV sets, the phosphor has some persistence. Movies are modulated with a square waves, the frame blinks off and goes dark then blinks on. But the LED's brightness is fast enough to track the sine wave and would be bright only for an instant with quick pulses of light. But just as bad as the flicker is that the LED is wasted and spends most of the time being dim. White LED's have phosphor in them also. That's how they convert the typically blue output to 'near full spectrum' white. I'm not sure about persistance in them though. I have some Cree XML's around here, and may try to see what a Photodiode can see when bursting them with PWM at various frequencies. I believe this also allows PWM dimming at relatively low frequencies. (--- See, frequency is time related ! :) ) Dan ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
snip I would hence believe that a 50 Hz flicker must be pretty close to the edge of what can be perceived, so I'm having trouble believing that a flicker at more than twice that rate would be perceptible at all by anyone. snip Oh, but it is. A couple of years ago I bought one of the Chinese 30 LED spot light bulbs for about $8 on ebay. I thought I'd give it a try for a workbench light. When I plugged it in at work (60 Hz power, here) the two guys standing behind me yelled gaahhh at the same time I did. The flicker was horrendous. The earlier comment about peripheral vision also applies, though. It's worse in the periphery than in direct view. The power supply is nothing more than a bridge rectifier, two current limiting resistors, and a filter capacitor. The capacitor obviously wasn't big enough, though, because it flcikered plenty. -John -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Dennis Ferguson Sent: Tuesday, September 18, 2012 1:52 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Hi Power LED Light power supply... On 18 Sep, 2012, at 12:42 , Chris Albertson wrote: On Tue, Sep 18, 2012 at 5:21 AM, Bob Camp li...@rtty.us wrote: Hi I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) In the old CRT type TV sets, the phosphor has some persistence. Movies are modulated with a square waves, the frame blinks off and goes dark then blinks on. But the LED's brightness is fast enough to track the sine wave and would be bright only for an instant with quick pulses of light. Just to add to this... Ontario, Canada originally ran its power grid at 25 Hz. When they switched the grid to 60 Hz in the 1930's some of the industrial power users, particularly in northern Ontario where private (usually hydroelectric) power generators were common, never got around to changing their plants over. Mine and paper mills using 25 Hz power were common as recently as the 1980's, and might still be there for all I know. Standard incandescent light bulbs don't have a lot of persistence when run on 25 Hz power (I assume there might have been a time when you could buy incandescent bulbs designed for 25 Hz, but not in my lifetime). They don't go entirely off, but they get significantly dimmer in the visible spectrum in the dips as the output red-shifts towards the infrared; they follow the sine pretty well. In my teens, when visiting a place using 25 Hz power for lighting, I could initially see an incredibly annoying flicker when I first got there but after a minute or two this would fade and I'd no longer notice it. Some other people would also see the flicker but others, including my parents, couldn't see it at all so there seemed to be variation (maybe age-related, maybe not) among individual abilities to see this. Dennis Ferguson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
There are ways for the flicker to be more evident. Don't laugh, but chewing something hard like a pretzel can bring out the flicker. Basically you can get beat patterns between the vibration of your eye and the light flicker. There is a common problem with DLP projectors that use color wheels. You will see reviewers shaking their heads and eat crunchy food in order to see rainbows on the screen. A similar problem occurs with matrixed LED displays mounted on machinery that has vibration. Very common in industrial controls since they like LEDs for readability. When I designed the 2nd generation LED display drivers, I bumped the refresh rate to 500Hz min. That was about 2x the frequency where I ran out of convoluted experiments to detect flicker. On an analog scope, you can display a flat line and have it wiggle by eating something crunchy. I don't have an analog scope on the bench at the moment, otherwise I would figure out the right circumstances to make that happen. The test pattern for flicker detection is to arrange LEDs where a group of them form a recognizable pattern. Take a plus sign as an example. Put the LEDs in an array. Illuminate the LEDs that are not in the symbol out of phase with those in the symbol. Vary the refresh rate. When the eye can see a pattern, the refresh rate is too low. On 9/18/2012 12:06 PM, John Lofgren wrote: snip I would hence believe that a 50 Hz flicker must be pretty close to the edge of what can be perceived, so I'm having trouble believing that a flicker at more than twice that rate would be perceptible at all by anyone. snip Oh, but it is. A couple of years ago I bought one of the Chinese 30 LED spot light bulbs for about $8 on ebay. I thought I'd give it a try for a workbench light. When I plugged it in at work (60 Hz power, here) the two guys standing behind me yelled gaahhh at the same time I did. The flicker was horrendous. The earlier comment about peripheral vision also applies, though. It's worse in the periphery than in direct view. The power supply is nothing more than a bridge rectifier, two current limiting resistors, and a filter capacitor. The capacitor obviously wasn't big enough, though, because it flcikered plenty. -John -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Dennis Ferguson Sent: Tuesday, September 18, 2012 1:52 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Hi Power LED Light power supply... On 18 Sep, 2012, at 12:42 , Chris Albertson wrote: On Tue, Sep 18, 2012 at 5:21 AM, Bob Camp li...@rtty.us wrote: Hi I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) In the old CRT type TV sets, the phosphor has some persistence. Movies are modulated with a square waves, the frame blinks off and goes dark then blinks on. But the LED's brightness is fast enough to track the sine wave and would be bright only for an instant with quick pulses of light. Just to add to this... Ontario, Canada originally ran its power grid at 25 Hz. When they switched the grid to 60 Hz in the 1930's some of the industrial power users, particularly in northern Ontario where private (usually hydroelectric) power generators were common, never got around to changing their plants over. Mine and paper mills using 25 Hz power were common as recently as the 1980's, and might still be there for all I know. Standard incandescent light bulbs don't have a lot of persistence when run on 25 Hz power (I assume there might have been a time when you could buy incandescent bulbs designed for 25 Hz, but not in my lifetime). They don't go entirely off, but they get significantly dimmer in the visible spectrum in the dips as the output red-shifts towards the infrared; they follow the sine pretty well. In my teens, when visiting a place using 25 Hz power for lighting, I could initially see an incredibly annoying flicker when I first got there but after a minute or two this would fade and I'd no longer notice it. Some other people would also see the flicker but others, including my parents, couldn't see it at all so there seemed to be variation (maybe age-related, maybe not) among individual abilities to see this. Dennis Ferguson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
On 18 Sep, 2012, at 15:06 , John Lofgren wrote: snip I would hence believe that a 50 Hz flicker must be pretty close to the edge of what can be perceived, so I'm having trouble believing that a flicker at more than twice that rate would be perceptible at all by anyone. snip Oh, but it is. A couple of years ago I bought one of the Chinese 30 LED spot light bulbs for about $8 on ebay. I thought I'd give it a try for a workbench light. When I plugged it in at work (60 Hz power, here) the two guys standing behind me yelled gaahhh at the same time I did. The flicker was horrendous. The earlier comment about peripheral vision also applies, though. It's worse in the periphery than in direct view. The power supply is nothing more than a bridge rectifier, two current limiting resistors, and a filter capacitor. The capacitor obviously wasn't big enough, though, because it flcikered plenty. Or could the problem have instead been that one side of the bridge wasn't working, so you were getting a 60 Hz flicker rather than 120 Hz? Having seen what I am sure was a 50 Hz flicker, I'd believe that 60 Hz might look awful but I still have some doubt about 120 Hz. Dennis Ferguson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
On Tue, Sep 18, 2012 at 2:27 PM, gary li...@lazygranch.com wrote: A similar problem occurs with matrixed LED displays mounted on machinery that has vibration. Very common in industrial controls since they like LEDs for readability. This is very evident on the new L train cars in Chicago. They have a multicolor LED sign for listing the train destination. For me at least the signs are unreadable when I try to read them from another moving train and hard to read from a platform when the structure vibrates. -- Ryan Szekeres KB9TQN ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
That's because the signs are scanned/multiplexed displays. It is not 60/120 Hz flicker. Tom - Original Message - From: Ryan Szekeres ryan.szeke...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, September 18, 2012 3:38 PM Subject: Re: [time-nuts] Hi Power LED Light power supply... On Tue, Sep 18, 2012 at 2:27 PM, gary li...@lazygranch.com wrote: A similar problem occurs with matrixed LED displays mounted on machinery that has vibration. Very common in industrial controls since they like LEDs for readability. This is very evident on the new L train cars in Chicago. They have a multicolor LED sign for listing the train destination. For me at least the signs are unreadable when I try to read them from another moving train and hard to read from a platform when the structure vibrates. -- Ryan Szekeres KB9TQN ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
Hi Oddly enough western New York State also had a 25 Hz grid. Something about Niagara Falls / George Westinghouse comes to mind. If as a youngster you rummaged around in the attic you could indeed find 25 Hz gear still sitting up there. Wish I'd kept it rather than parted it out. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Dennis Ferguson Sent: Tuesday, September 18, 2012 2:52 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Hi Power LED Light power supply... On 18 Sep, 2012, at 12:42 , Chris Albertson wrote: On Tue, Sep 18, 2012 at 5:21 AM, Bob Camp li...@rtty.us wrote: Hi I suspect those same 120Hz sensitive people would not be able to watch TV or a movie :) In the old CRT type TV sets, the phosphor has some persistence. Movies are modulated with a square waves, the frame blinks off and goes dark then blinks on. But the LED's brightness is fast enough to track the sine wave and would be bright only for an instant with quick pulses of light. Just to add to this... Ontario, Canada originally ran its power grid at 25 Hz. When they switched the grid to 60 Hz in the 1930's some of the industrial power users, particularly in northern Ontario where private (usually hydroelectric) power generators were common, never got around to changing their plants over. Mine and paper mills using 25 Hz power were common as recently as the 1980's, and might still be there for all I know. Standard incandescent light bulbs don't have a lot of persistence when run on 25 Hz power (I assume there might have been a time when you could buy incandescent bulbs designed for 25 Hz, but not in my lifetime). They don't go entirely off, but they get significantly dimmer in the visible spectrum in the dips as the output red-shifts towards the infrared; they follow the sine pretty well. In my teens, when visiting a place using 25 Hz power for lighting, I could initially see an incredibly annoying flicker when I first got there but after a minute or two this would fade and I'd no longer notice it. Some other people would also see the flicker but others, including my parents, couldn't see it at all so there seemed to be variation (maybe age-related, maybe not) among individual abilities to see this. I would hence believe that a 50 Hz flicker must be pretty close to the edge of what can be perceived, so I'm having trouble believing that a flicker at more than twice that rate would be perceptible at all by anyone. Dennis Ferguson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
On Tue, Sep 18, 2012 at 2:46 PM, Tom Miller tmil...@skylinenet.net wrote: That's because the signs are scanned/multiplexed displays. It is not 60/120 Hz flicker. Tom Something new to research. Thanks! -- Ryan Szekeres KB9TQN ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PLL behavior
On 09/18/2012 05:28 PM, Jim Lux wrote: I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're not trying to track noise).. What I'm particularly interested in is the behavior in the PLL when the reference returns. The overall situation is where we are trying to make a frequency/phase measurement over 10-100 seconds, where the reference has a 50% duty cycle, and is on for a second, off for a second. I can fairly simply model this, or just try it, but I'm looking for some references to an analytical approach. The leakage of your filter will cause the frequency to have drifted a little during the off period, so one way of modelling it would be that you would treat it like a frequency step. However, if you think a little about it, the drift will most likely not be that great so you would only shifted a somewhat in phase, and what you get is a phase step response. It's really trivial to analyze and it has already been done to great extent. It helps if you realize that a dirac delta has the LaPlace form of I(s) = 1, and then that a phase step has the formula I(s) = /|phi / s and that a phase ramp/frequency step has the formula I(s) = /|omega / s^2. Applying these I(s) to you PLLs H(s) gives you the O(s) for your response to these stress-tests. Apply inverse LaPlace transform for impulse responces. You can cheat and look it up in standard books. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PLL behavior
On 09/18/2012 06:15 PM, Bob Camp wrote: Hi Gardner in Phaselock Techniques has figure 4.8 that is a pretty good starting point. In general, it's a really good book to read. Gardner covers this field well, and even if some of the stuff I needed wasn't in there, it was an excellent startingpoint. I rather have people first read Gardner thoroughly then reading the Best book randomly. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
That is a very fun prank to do. Show someone an o'scope with a flat line on it and hand them a pretzel or carrot. Tell them that you have implanted several sensors into their brain and you want to calibrate them starting with mandibular vibration. I have seriously freaked some people out with this one. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of gary Sent: Tuesday, September 18, 2012 12:28 To: time-nuts@febo.com Subject: Re: [time-nuts] Hi Power LED Light power supply... There are ways for the flicker to be more evident. Don't laugh, but chewing something hard like a pretzel can bring out the flicker. Basically you can get beat patterns between the vibration of your eye and the light flicker. There is a common problem with DLP projectors that use color wheels. You will see reviewers shaking their heads and eat crunchy food in order to see rainbows on the screen. A similar problem occurs with matrixed LED displays mounted on machinery that has vibration. Very common in industrial controls since they like LEDs for readability. When I designed the 2nd generation LED display drivers, I bumped the refresh rate to 500Hz min. That was about 2x the frequency where I ran out of convoluted experiments to detect flicker. On an analog scope, you can display a flat line and have it wiggle by eating something crunchy. I don't have an analog scope on the bench at the moment, otherwise I would figure out the right circumstances to make that happen. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
Only one LED per segment is on. They are arranged in a matrix -- keeps the pin count down to a dull roar. http://www.instructables.com/id/LED-Dot-Matrix-Display/ http://www.electronics-lab.com/projects/misc/013/index.html DaveH -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ryan Szekeres Sent: Tuesday, September 18, 2012 12:55 To: Tom Miller; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Hi Power LED Light power supply... On Tue, Sep 18, 2012 at 2:46 PM, Tom Miller tmil...@skylinenet.net wrote: That's because the signs are scanned/multiplexed displays. It is not 60/120 Hz flicker. Tom Something new to research. Thanks! -- Ryan Szekeres KB9TQN ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Reducing lab noise with LED lighting.
Has anyone tried the fluorescent replacement LED tubes? Apparently you remove the ballast from the fixture and power the tube from the 120V AC line. Any chance these would reduce the noise in a lab from conventional fluorescent tubes? Thanks. attachment: smither.vcf___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
dennis.c.fergu...@gmail.com said: [context is flicker from light bulbs running on 25 Hz power] I would hence believe that a 50 Hz flicker must be pretty close to the edge of what can be perceived, so I'm having trouble believing that a flicker at more than twice that rate would be perceptible at all by anyone. It depends a lot on the intensity and the modulation percentage. (and other things) LEDs are probably the worst case: very bright (locally) and 100 % modulation if the filter is crappy. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
The LED traffic signals around here are super noisy electrically. They rip up my mobile gear from the AM broadcast band through 2 meters any time we are close to a traffic light. Some are worse than others. If you can find out who makes them then avoid that manufacture like the plague. Al, k9si Date: Tue, 18 Sep 2012 13:23:41 -0400 (EDT) From: k3...@aol.com To: time-nuts@febo.com Subject: Re: [time-nuts] Hi Power LED Light power supply... If you all check, they are using LEDs in traffic signals now by the thousands. These are variations of multiple LEDs used in these signals and they are all powered by 115vac thru the traffic controllers. Joe k3wry ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED --- Thread Overload
Fellow Time Nuts, in the last week we had more than 50 emails concerning Fedex versus UPS shipping and how to package something, now we have a similar number of emails about LED lighting. I hope we can end this thread soon, or move it to another discussion group. I for one am getting really tired of deleting 50+ emails every day that are not related to time or frequency metrology. Thanks, Said That is a very fun prank to do. Show someone an o'scope with a flat line on it and hand them a pretzel or carrot. Tell them that you have implanted several sensors into their brain and you want to calibrate them starting with mandibular vibration. I have seriously freaked some people out with this one. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of gary Sent: Tuesday, September 18, 2012 12:28 To: time-nuts@febo.com Subject: Re: [time-nuts] Hi Power LED Light power supply... There are ways for the flicker to be more evident. Don't laugh, but chewing something hard like a pretzel can bring out the flicker. Basically you can get beat patterns between the vibration of your eye and the light flicker. There is a common problem with DLP projectors that use color wheels. You will see reviewers shaking their heads and eat crunchy food in order to see rainbows on the screen. A similar problem occurs with matrixed LED displays mounted on machinery that has vibration. Very common in industrial controls since they like LEDs for readability. When I designed the 2nd generation LED display drivers, I bumped the refresh rate to 500Hz min. That was about 2x the frequency where I ran out of convoluted experiments to detect flicker. On an analog scope, you can display a flat line and have it wiggle by eating something crunchy. I don't have an analog scope on the bench at the moment, otherwise I would figure out the right circumstances to make that happen. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] High Power LED Light power supply...
I spent many years as an electrician/electronics technician in a performing art center. Many artists would simply not practice or perform under fluorescent light because of the supposed flicker issue. Many of those who had no choice complained about it. Dancers were the worst. Al, k9si Date: Tue, 18 Sep 2012 11:47:50 -0600 From: Tom Knox act...@hotmail.com To: Time-Nuts time-nuts@febo.com Subject: Re: [time-nuts] Hi Power LED Light power supply... I think that even flicker you cannot consciously see, subconsciously can have effects of mental fatigue and eye strain. This is why most florescent fixtures are in pairs firing at 180 degrees. An optical sensor on a scope should allow the power supply to be tweaked for a steady light. Thomas Knox ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PLL behavior
On 9/18/12 1:49 PM, Magnus Danielson wrote: On 09/18/2012 05:28 PM, Jim Lux wrote: I'm looking for info on behavior of a PLL (with VCXO) when the reference comes and goes periodically. When the reference is gone, the PLL will flywheel according to whatever the loop filter does. (we can turn off the input to the filter, so we're not trying to track noise).. What I'm particularly interested in is the behavior in the PLL when the reference returns. The overall situation is where we are trying to make a frequency/phase measurement over 10-100 seconds, where the reference has a 50% duty cycle, and is on for a second, off for a second. I can fairly simply model this, or just try it, but I'm looking for some references to an analytical approach. The leakage of your filter will cause the frequency to have drifted a little during the off period, so one way of modelling it would be that you would treat it like a frequency step. However, if you think a little about it, the drift will most likely not be that great so you would only shifted a somewhat in phase, and what you get is a phase step response. It's really trivial to analyze and it has already been done to great extent. It helps if you realize that a dirac delta has the LaPlace form of I(s) = 1, and then that a phase step has the formula I(s) = /|phi / s and that a phase ramp/frequency step has the formula I(s) = /|omega / s^2. Applying these I(s) to you PLLs H(s) gives you the O(s) for your response to these stress-tests. Apply inverse LaPlace transform for impulse responces. That is basically what I have now.. I guess the next question that leads to is how big is the phase step, and that depends on what the oscillator did (in a statistical sense) during the flywheel time, which in turn, I should be able to figure out from the Allan Deviation data. A lot of classical loop analyses (in terms of the statistics) makes the assumption that the phase detector response is linear (that is, that the error signal is linearly proportional to phase error), which is reasonable for small delta phase. But in the phase step case, that might not be. I suppose then, it's more like looking at the acquisition behavior analysis. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hi Power LED Light power supply...
On 9/18/12 10:57 AM, Tom Knox wrote: I remember reading that Hollywood played with faster frame rates and found a substantial number of people experience motion sickness. Not so much the frame rate, but generating imagery that isn't realistic.. your eye expects motion blur (particularly in projected images), and if you project a series of very sharp frames with lots of depth of field, it confuses your brain, because it's trying to process out the motion, but the cues are a little bit off. One cause of motion sickness, for that matter, is where the image your eye sees doesn't match the signals from the vestibular canals. The original Star Tours at Disneyland was quite noticeable for this, because it used a lot of rotation movements (which shift the local G vector) to simulate acceleration since it had limited travel on the motion base. i.e. if you keep the forward view constant and showing an acceleration, and tilt your chair back, the force pushing you back into the chair matches what you'd expect from the visual cue, except for the rotation. Some people didn't get affected much, others did (it made me quite nauseous, while a standard roller coaster doesn't). And images that move with a lag relative to your head motion are notorious (early 3 D graphics goggle displays with a Polhemus head position sensor..) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PLL behavior
On 9/18/12 9:48 AM, Raj wrote: If you break the DC control chain of the PLL with a A2D and a controller and back with a D2A .. you would program the control with any kind of behavior you want. Just a thought! That is exactly what we do... the PLL is actually implemented digitally (DAC driving the VCO).. But what I'm looking for is a theoretical treatment of the output statistics (Allan Dev, mostly) in terms of the interrupted reference input. For context.. we do precision ranging of spacecraft in deep space by sending a hydrogen maser derived signal TO the spacecraft which locks a local VCXO to that signal, and then uses the VCXO to generate a return signal with a constant ratio (e.g. 880/741) to the input. By measuring the time it takes for the round trip (essentially counting phase cycles on the return signal (against our hydrogen maser, again), we measure Range and Doppler, which is then used to determine the position of the spacecraft. Typical performance is sub-meter and sub cm/sec. (A very high performance would be that the transponder adds 4E-15 Allan Dev over 1000 sec... 1E-11 or 1E-12 over 10-100 secs is more usual) What we want to know is what happens if the receiver and transmitter can't run at the same time? Obviously, we have less information coming into the system (we see the uplink half the time, so right there, we have a 2:1 hit) and the ground end only sees the transmit signal half the time (another 2:1 hit), so, from an information theory standpoint we've already put ourselves in a hole, but, what does the statistics really look like for the turnaround loop.. Full Duplex full power turnaround is expensive in power, mass, etc. (for instance, you have to have good filters to make sure that your receiver isn't corrupted by the transmitter) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Reducing lab noise with LED lighting.
I've tried that with a replacement tube that worked with the original ballast, all you had to do was remove the starter. The results were horrible. The tube was about a metre above my scope and waving the probe about showed horrible spikes and damped oscillatory waveforms up to several volts in amplitude. Needless to say I'm back to a conventional fluoro. The discussion about LED flicker was interesting. As I understand it the human eye can act as a peak detector so it responds quite well to pulsed lights at a high enough frequency. I'm currently (boom boom) illuminating an ornamental vacuum tube display with a strip of white LEDs powered by full wave rectified but unfiltered DC at 100 Hz (in a 50 Hz country). It's in an otherwise dim corner and there's never been any hint of visible flicker to me or anyone else. Morris Date: Tue, 18 Sep 2012 17:22:44 -0500 From: Bob Smither smit...@c-c-i.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Reducing lab noise with LED lighting. Has anyone tried the fluorescent replacement LED tubes? Apparently you remove the ballast from the fixture and power the tube from the 120V AC line. Any chance these would reduce the noise in a lab from conventional fluorescent tubes? Thanks. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Reducing lab noise with LED lighting.
On Tue, Sep 18, 2012 at 7:49 PM, Morris Odell vilgo...@bigpond.net.au wrote: The discussion about LED flicker was interesting. As I understand it the human eye can act as a peak detector Actually the rods and cones in the retina only respond the changes in brightness. the eye constantly moves so that the image always changes. It works this way because we needed to see only edges. We don't see 120Hz as flicker but still it stresses the eyes and visual system. If you think of the eye as being AC coupled to the brain it is easy to understand why to fast to see fast flicker is fatiguing. Back to noise in the lab: As I wrote a while back if you want efficient lighting that is radio quiet all you have to do is shop in the right store. Much of the lighting used in ocean going sail boats is quiet because these boats will cary HF and VHF radio, GPS and radar and run off battery power. But don't expect radio-quiet cold cathode fluorescent lamps made from power coated stainless steel to be cheap, you pay for the quality. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] HP-106 and Sulzer Quartz Crystals
Hi: Does anyone know who made the crystal for the HP-106 and / or Sulzer oscillators? Is Bliley Electric Company still in business? They use to sell a 5th overtone precision quartz crystal for frequency standard use. Where could you find the ultimate crystal today for a frequency standard? Thanks, Ron ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
